Correct X-ray views is important in the management of fractured ankles and in determining the treatment choice for the ankle fracture. There are generally three X-ray views used to evaluate an ankle fracture which are the anteroposterior (AP) view or the mortise view, the lateral or side view, and the calcaneal or back view of the ankle. It has been shown that the mortise view is the most reliable for use in the assessment of ankle congruity where the foot is internally rotated approximately 20° while the foot is maintained at a 90° angle relative to the leg. In such position, the medial and lateral malleoli of the leg are projected without the projection of the talus over the medial and lateral malleolus.
Obtaining accurate mortise views usually depend on the experience of radiographers and it is not uncommon for incorrect views to be sent to a surgeon. These errors are usually as a result of the variability associated with routine, freehand positioning of the ankle by the radiographers. In such cases, these incorrect views are sent for repeat X-rays until adequate views for evaluation are obtained. This causes unnecessary radiation exposure to a patient and usually involves additional costs.
A device is known which attempts to alleviate the above mentioned problem by maintaining an ankle in an optimal standardized position while procuring the mortise radiographic image. This device is disclosed in The Journal of Foot and Ankle Surgery by Donken, Christian CMA, et al., with title “Use of an Acrylic Mold for Mortise View Improvement in Ankle Fractures: A Feasibility Study”. This device comprises a transparent acrylic positioning jig or mould consisting four 4-mm-thick panels of radiolucent acrylic material (transparent polymethyl methacrylate). The first panel is a rectangular base with the second panel extending from a short side thereof. The first and second panels support the two remaining panels which diverge from the middle of the base at −25° and 25° angles relative to a vertical and longitudinal plane through the base.
The acrylic jig is used to position an injured foot of a patient lying on a radiographic examination table in the supine position with the ankle maintained at a 90° angle relative to the leg and with the foot rotated inwardly at about 25°. An X-ray image of the ankle may then be captured. The acrylic jig does not provide for the taking of the AP mortise views at different inwardly rotated angular displacements of the foot at specific angles of less than the 25° and also does not provide for the taking of the calcaneal view of the ankle. Further, the second foot of the patient has to be placed independently in the acrylic jig in a separate procedure and X-ray images of the second foot may then be captured for comparative purposes. The divergent panels of the jig also extend up an appreciable height of the leg, namely about 500 mm.
There is a need for an ankle imaging accessory that can be used by a radiographer to obtain better and more accurate mortise views of an ankle conveniently and which alleviates the above mentioned problems at least to some extent.
In the remainder of the specification the term “X-ray translucent material” should be construed widely and shall include all materials that would allow an X-ray image to be taken therethrough, including X-ray translucent material, X-ray transparent material, radiolucent structural materials, and the like.
The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.